1. Field of the Invention
The present invention relates to novel imido polymers, and, more especially, to novel imido polymers comprising the copolymerizates of at least one N,N'-bisimide, at least one hindered diprimary diamine, and at least one chlorinated/brominated epoxy resin, N,N'-alkylenebistetrahalophthalimide and/or (meth)allyloxylated aromatic comonomer bearing at least two chlorine or bromine substituents.
2. Description of the Prior Art
French Patent Application FR-A-2,608,613 describes polymers containing imide groups, which can be in the form of heat-curable prepolymers, which comprise the product of reaction, at a temperature ranging from 50.degree. C. to 300.degree. C., between:
(a) one or more N,N'-bisimides having the formula: ##STR1## in which the symbols Y, which may be identical or different, are each H, CH.sub.3 or Cl; the symbol A is a divalent radical selected from among cyclohexylene, a phenylene, 4-methyl1,3-phenylene, 2-methyl1,3-phenylene, 5-methyl1,3-phenylene, 2,5-diethyl-3-methyl1,4-phenylene, or a radical of the formula: ##STR2## in which T is a single valence bond or one of the groups: ##STR3## and the symbols X, which may be identical or different, are each a hydrogen atom or a methyl, ethyl or isopropyl radical; PA1 (b) one or more hindered diprimary diamine(s) selected from among: PA1 (c) optionally, one or more nonhalogenated monomer(s) other than a bisimide of formula (I) and containing one or more polymerizable carbon-carbon double bond(s); and, optionally PA1 (d) an imidazole compound PA1 (c2) or a compound comprising:
(i) compounds having the general formula: ##STR4## in which the symbols R.sub.1, R.sub.2, R.sub.3 and R.sub.4, which may be identical or different, are each a methyl, ethyl, propyl or isopropyl radical; the symbols Z, which may be identical or different, are each a hydrogen atom or a chlorine atom; and PA2 (ii) compounds having the general formula: ##STR5## in which the amino radicals are in a meta or para position relative to each other; and the symbols R.sub.5, which may be identical or different, are each a methyl, ethyl, propyl or isopropyl radical; PA2 (i) a mixture of a monomer of the formula: ##STR11## in which the allyloxy or methallyloxy radical is in an ortho, meta or para position relative to the carbon atom of the benzene ring bonded to the nitrogen atom, with: PA2 (ii) at least one monosubstituted compound of the formula: ##STR12## and, optionally, (iii) one or more disubstituted compounds of the formula: ##STR13##
A first advantage associated with the polymerization described in the aforesaid French application stems from the steric hindrance of the amine reactant (b), which is responsible for a lower reactivity of the constituents of the polymerization mixture, vis-a-vis the polyamino bismaleimides produced from unhindered diamines. This lower reactivity of the constituents of the polymerization mixture is of particular interest, not only for the manufacture of articles depending on a conversion of a prepolymer in the molten state, but also for the production of articles depending on a conversion of a prepolymer in the form of a solution in a solvent. Indeed, the viscosity of the prepolymer in the molten state, or that of the prepolymer solution, changes more slightly and this makes the conversion of the prepolymer much easier, especially in applications requiring a working life of several hours.
A second advantage of the polymerization described in the aforesaid French application resides in the fact that the polymers are prepared without taking special precautions from the standpoint of health and hygiene, given that the hindered diamines (b) do not present the toxicity hazards which are generally associated with unhindered aromatic diprimary diamines.